a) Field of the Invention
The invention is directed to a regulating vacuum valve. In particular, the invention is directed to a regulating vacuum valve comprising a valve housing with a through-channel, first and second valve plates which lie in adjacent and parallel planes and are mounted so as to be adjustable in their planes and can be moved into the through-channel from different sides proceeding from an open position in which they lie laterally adjacent to the through-channel to form a through-opening whose size is adjustable.
b) Description of the Related Art
There are different known embodiment forms of regulating vacuum valves in which the through-cross section of the valve is adjustable and a valve plate is displaceable between a position laterally adjacent to the through-channel and a position in which the through-channel is covered. Stepping motors, for example, can be used for displacing the valve plate. In this connection, there are known regulating vacuum valves which are used only for regulating and which still have a certain residual conductivity even when closed as far as possible, and there are those which also have a sealed state in which they are closed so as to be vacuum-tight.
The displacement of the valve plate can be carried out linearly or, in case of a so-called pendulum slide, the valve plate can be adjusted by a swiveling movement around an axis vertical to the valve plate.
U.S. Pat. No. 5,577,707 discloses a vacuum valve which has a valve plate that is laterally adjacent to the valve opening in the open state and is displaceable into a position in which the valve opening is covered in order to close the valve. A ring-shaped seal connection piece is provided for sealing the valve plate relative to the valve body in the sealed state of the valve. The seal connection piece is mounted in the through-channel so as to be displaceable vertical to the plane of the valve plate and is tightly fitted to the valve plate in the sealed state of the valve. The contents of the text cited above are hereby adopted in the present application through reference.
Another vacuum valve of this type with a seal connection piece which can be adjusted to the valve plate for sealing the valve and in which, in addition, the conductivity of the valve can also be regulated is known from U.S. Pat. No. 5,873,562, whose contents are likewise adopted through reference. This patent also mentions additional references, e.g., U.S. Pat. No. 3,145,969, disclosing seal connection pieces which are adjustable at the valve plate.
A disadvantage in U.S. Pat. No. 5,873,562 consists in that the orifice opened in the regulating area is not symmetric to the axis of the through-channel so that the gas flow through the valve is asymmetric, which is undesirable in various applications, for example, in semiconductor technology.
U.S. Pat. No. 6,325,096 shows and describes various embodiment examples of regulating valves in which a symmetric flow is achieved in the regulating area. In this connection, band-shaped or plate-shaped closure members are displaced simultaneously, so that the through-cross section of the through-channel is narrowed from opposite sides simultaneously and the remaining through-opening is symmetric to the axis of the through-channel. This regulating valve has no sealed state.